Swift String extension to get crypto hashes

gistfile1.swift

// Based on:
//  https://github.com/mnbayan/StringHash
//  https://github.com/hypercrypt/NSString-Hashes

enum HashType {
    case MD5
    case SHA256
    case SHA512
}

extension String {
    
    func getCryptoHash(type: HashType) -> String {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = CC_LONG(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen: Int
        let result: UnsafeMutablePointer<CUnsignedChar>
        
        switch type {
        case .MD5:
            digestLen = Int(CC_MD5_DIGEST_LENGTH)
            result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
            CC_MD5(str!, strLen, result)
        case .SHA256:
            digestLen = Int(CC_SHA256_DIGEST_LENGTH)
            result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
            CC_SHA256(str!, strLen, result)
        case .SHA512:
            digestLen = Int(CC_SHA512_DIGEST_LENGTH)
            result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
            CC_SHA512(str!, strLen, result)
        }
        
        var hash = NSMutableString()
        for i in 0..<digestLen {
            hash.appendFormat("%02x", result[i])
        }
        
        result.destroy()
        
        return String(format: hash as String)
    }
}